A. Field of the Invention
This invention relates to dialysis machines, and more particularly to hemodialysis machines that have an extracorporeal blood circuit in which a priming fluid is circulated through the extracorporeal circuit. The priming fluid is used to remove air bubbles and manufacturing-related contaminants contained within the blood tubing set and blood side of the dialyzer prior to the introduction of the patient's blood into the machine. The invention could be practiced in other similar types of machines, such as a liver dialysis machine.
B. Description of Related Art
Hemodialysis machines are used for treating patients with inadequate kidney function. Hemodialysis machines include, among other things, an extracorporeal blood circuit typically comprising an arterial line, a blood pump, a dialyzer and a venous line. Blood is removed from the patient via the arterial line and pumped by the blood pump to the dialyzer, where blood-borne toxins and excess fluids are removed from the patient's blood. The blood is then returned to the patient via the venous line.
It is known in the art to prime the extracorporeal circuit prior to the dialysis session to remove air and residual contaminants from the blood tubing set and blood side of the dialyzer. The priming fluid is typically a physiologic solution such as either a dialysate solution or a saline solution. In the prior art, the priming solution is returned to the patient via the venous line when blood is introduced into the arterial line. Alternatively, as the blood is introduced into the arterial line, the venous line is held over a receptacle such as bucket and the priming fluid is emptied into the receptacle exterior of the extracorporeal circuit. Both of these approaches have disadvantages. Returning the fluid to the patient compounds the patient's need to have fluid removed from the patient and prolongs, for many patients, the time required for dialysis. Dumping the priming fluid into a receptacle presents an obvious disposal and inconvenience problem, as well as the potential for contamination of the venous line connector and other sanitary problems since the operator will typically have to handle the venous line connector when the priming fluid is being disposed of in the receptacle.
The present invention avoids the above difficulties by providing a method of removing the priming fluid from the extracorporeal circuit that can prevent the priming fluid from being returned to the patient, without requiring any external receptacles to receive the priming fluid, and without exposing the venous lines or the patient to additional risks of contamination, such as may occur by the patient's hands or clothing coming into contact with the connectors terminating the blood tubing set.